Non-invasive Imaging of the In Situ Restoration of Brain Tissue Abstract Regenerative medicine is gradually merging the use of stem cells and biomaterials into tissue engineering to repair damaged tissues. Developments in tissue engineering of the brain have been slow, mostly due to accessibility of the brain and being able to monitor the ongoing process non-invasively. However, non-invasive imaging, such as MRI, provides information as to the site and extent of damage in the brain, affording image- guided injection of material for tissue engineering. However, little progress has been achieved in monitoring implanted cells, as well as biomaterial non-invasively. One major challenge is to visualize these different components non-invasively without the detection of one affecting the detection of the other, or potentially the visualization of brain damage. A significant development of non-invasive imaging is therefore needed to facilitate our ability to monitor the evolution of i situ tissue engineering inside the brain. Specifically, we here aim to: 1) develop magnetic resonance imaging-based paramagnetic chemical exchange saturation transfer (PARA-CEST) to distinguish human neural stem cells (NSCs) and human endothelial cells (ECs) and 2) establish a CEST based imaging of a de-cellularized extracellular matrix (ECM) bioscaffold without interfering with our ability to detect a stroke-induced lesion cavity. These studies will provide the framework to monitor in situ tissue engineering for stroke.